Groundwater recharge and evapotranspiration are often strongly related to precipitation in temperate regions. However, climate change is expected to change precipitation patterns and alter evapotranspiration, which will inevitably have consequences for the fraction of precipitation that ultimately turns into recharge. Since evapotranspiration is highly sensitive to climate, predictions of future groundwater recharge depend on accurate representation of this parameter. Factors that shape evapotranspiration in vegetated regions are soil water availability, plant water use efficiency, global radiation and vapor pressure deficit, among others, all of which directly or indirectly affect plant water use. How plants adapt their water use to a changing climate is thus highly informative for predictions of future groundwater recharge.

Current climate models indicate an increase in potential evapotranspiration, especially under scenarios with strong CO2 emissions. But it is still far from clear whether actual evapotranspiration will also increase, especially in regions where summer-time ET is usually water-limited rather than energy-limited and how this affects recharge.

We simulated the consequences of increases in atmospheric CO2 and temperatures for both, evapotranspiration and groundwater recharge, and found that the results are very different for specific vegetations types. For example, some plants will experience an elongation of the growing period, thereby theoretically increasing annual soil water demand. But the growing season for crops may shorten because of faster growing and ripening, so that harvest may occur earlier in the year, thereby decreasing plant soil water demand. Increasing atmospheric CO2 will increase plant-water use efficiency, so that crops may need less water to grow. For trees the picture is even more complicated. Warming spring temperatures may lead to an earlier leafing, but soil water stress at the end the growing season may actually shorten the growing period of trees. Further an increase in leaf area will lead to more transpiration by trees through increased soil-water uptake by roots. But soil evaporation might decrease, as large canopy shading reduces sunlight reaching the ground under trees.

The net effect of plant water use and on groundwater recharge is worth studying, especially under the conditions of climate change, because groundwater will likely remain a valuable resource for future human water consumption.

How to cite: Riedel, T., Weber, T., and Bergmann, A.: Groundwater recharge, vegetation and climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5747, https://doi.org/10.5194/egusphere-egu24-5747, 2024.

In the face of intensified climatic extremes and global aquifer stress, a subtle understanding of the complex dynamics of large aquifer systems is necessary. This study delves into the impact of changing climate and anthropogenic activities on hydro-geologically diverse regions crucial for sustaining agricultural activities. Our central hypothesis is that excessive anthropogenic activities may disrupt the connection between groundwater levels and their primary recharge source—precipitation. Leveraging advanced non-linear signal processing technique of cross-wavelet transform, we explore non-linear relationships between groundwater and precipitation. Our findings underscore the complexity of interactions between surface and sub-surface processes in the sub-tropical basins.  A crucial threshold emerges at the basin scale, as the disconnection occurs when the water table falls below 4-5 meters. Intriguingly, at the basin and subbasin scale, the connection between groundwater and precipitation has significantly weakened and broken post the drought year 2002, emphasizing the localized and enduring impact of pumping activities. The recovery from these extremes, vital for sustaining agriculture, is intricately linked to the intensity of anthropogenic activities. This research contributes valuable insights into how the groundwater response to precipitation is changing with time in highly developed large subtropical aquifers facing increasing frequency of droughts. The results will aid in formulating region-specific groundwater management strategies to enhance the resilience of groundwater resources to global warming and climate change.

How to cite: Bhatnagar, I., Rahmati, M., Hendrick Franssen, H., Dhanya, C. T., and Chahar, B. R.: Discovery of Resilience of Large and Complex Aquifers to Climatic Extremes under Anthropogenic Influences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-231, https://doi.org/10.5194/egusphere-egu24-231, 2024.

Groundwater resources in arid regions play a crucial role in meeting water demands; however, they are facing rapid depletion due to unsustainable exploitation practices, exacerbated by climate change. As climate extremes intensify, there is a growing emphasis on harnessing flood and storm flows to replenish overdrawn aquifers. Floods can present a unique opportunity for restoring groundwater levels and mitigating saltwater intrusion into aquifers. The use of effectively managed floodwater for aquifer recharge offers a dual advantage by maximizing the potential of floods as a valuable water resource, while minimizing their negative impacts.

This work proposes an integrated approach to evaluate the geospatial suitability of groundwater recharge using floodwater across Qatar, a peninsula located in the eastern part of the Arabian Peninsula. We applied a Quantum GIS-based Multi-Criteria Decision Analysis (MCDA) approach, namely the Analytic Hierarchy Process (AHP), to delineate flood susceptible zones and groundwater recharge zones in Qatar, considering several influential topographical, hydrological, environmental, and anthropological criteria. The maps of flood susceptibility and potential groundwater recharge zones were validated using recent flooding events and existing recharge wells data, respectively. Sensitivity analysis was conducted on both variables to further assess their accuracy. The overlay analysis of the two validated maps, encompassing 98% of the entire country's surface, suggests that approximately 64% of the Qatar peninsula presents medium to excellent suitability for aquifer recharge using floodwater. The areas best suited for floodwater-based recharge intervention are located in the northern and coastal regions of the peninsula, while the urban areas and southwestern area are less suitable.

The findings of this study provide decision-makers with spatially explicit information for targeted aquifer recharge projects, potentially mitigating groundwater depletion, enhancing water security, and improving flood risk management in Qatar. In addition, we offer insights into further investigation areas, encompassing technical, economic, and regulatory considerations, to enhance the applicability and effectiveness of the proposed groundwater recharge strategies. The approach employed can be effectively applied in similar flood-prone arid regions and is adaptable to diverse contexts.

How to cite: Aloui, S., Zghibi, A., Mazzoni, A., Elomri, A., and Al-Ansari, T.: Towards an Integrated Groundwater Management and Flood Control in Arid Qatar: Insights from GIS-Driven Multi-Criteria Decision Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4580, https://doi.org/10.5194/egusphere-egu24-4580, 2024.

We present a panel of numerical modeling studies aimed to improve groundwater management resources for different contexts in the Northern part of France (the 'Hauts-de-France' Region). The objective is to demonstrate the capacities and limitations of modeling tools in reproducing observed data and providing predictions on the groundwater evolution under increasing anthropic pressures and climate change. Numerical models are developed in 3D at the regional scale to evaluate various scenarios of groundwater management, considering several types of anthropic or natural constraints such as pumping for irrigation, drinking water and/or industrial use, land use evolution, and modifications in precipitation and/or evapotranspiration due to climate change.

In the three case studies presented, groundwater models are developed using BRGM’s 3D volume finite numerical tool MARTHE. The first case aims to characterize groundwater dynamics to identify the risks of flooding in the sewerage network of the urban communities of Lens-Liévin. The second case explores the role of land use in groundwater modeling for the sustainable management of the Lille Metropolitan Area. The third case evaluates the impact of climate change on the groundwater resource of the Somme River watershed.

Limitations and capacities to assess such complex hydrogeological systems are discussed, particularly concerning the uncertainty in the simulated results, the CPU time and space resolution constraints necessary for a meaningful calibration of observed data.

How to cite: Audigane, P., Picot-Colbeaux, G., Aissat, R., Buscarlet, E., and Amraoui, N. and the URBEAU, CALL and AMEVA SOMME Project Teams: Modeling Groundwater Resource in Northern France Amidst Rising Anthropogenic Pressure and Climate Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11526, https://doi.org/10.5194/egusphere-egu24-11526, 2024.

As a result of climate change, periods of drought are likely to be longer and more frequent. Many small and medium-sized rivers are already drying up in summer and becoming temporary watercourses with all the limiting factors such as oxygen deficiency, excessively high temperatures and their effects on aquatic fauna in particular.

One way to counteract the drying up of impacted rivers is to artificially recharge the alluvial aquifers that feed the rivers via a geoengineering method called Managed Aquifer Recharge (MAR). There are various infiltration-based methods employed in MAR, including groundwater recharge via natural and technical infiltration basins or particularly in built-up areas with injection wells that recharge the water directly into the aquifer. The enhanced exfiltration of groundwater as a result from MAR to targeted rivers is called Managed Surface Water Recharge (MSWR). By artificially raising the groundwater level using MAR from nearby rivers/basins to such an extent that the groundwater level is subsequently hydraulically higher than the river level, so that the groundwater can flow into the rivers affected by drought.

To sustainably achieve MSWR, MAR should take place when surface water is abundant during medium and high river discharge periods such that groundwater later can exfiltrate into rivers during low water periods. Another positive effect of MSWR lies in the fact that low water periods and drought often occur during hotter summer months. While MAR is often optimal during the cooler snowmelt periods or rain intensive transitional seasons, resulting in comparatively lower temperature of water entering into the ground. MSWR is thus often automatically accompanied by an ecohydrologically relevant cooling effect achieved via the enhanced exfiltration of comparatively cooler groundwater during hotter summer periods. Thus, in addition to an increase in groundwater exfiltration into surface waters during drought periods, MSWR also has the benefit of ecological enhancement in rivers with respect to water temperature and quality.

Here, we present first results of our current research into practical MAR-MSWR, which we have conducted at different sites in urban and rural environments in pre-Alpine Switzerland. We present process-based results for different spatial, temporal and operational scales including both local (river-reach) as well as regional (river-basin) perspectives.

How to cite: Epting, J., Affolter Kast, A., Scheidler, S., Råman Vinnå, C. L., and Schilling, O. S.: Measures to adapt to climate change and mitigate the impact of droughts in alluvial aquifers and rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16458, https://doi.org/10.5194/egusphere-egu24-16458, 2024.

Climatology and hydrology depend significantly on the precise spatial characterization of their variables on continuous surfaces. The interpolation of hydrometeorological data emerges as an essential component, allowing for the estimation of values between observation points and facilitating the creation of detailed and comprehensive datasets. This process is crucial for understanding the climatic and hydrological conditions of watersheds. This work describes applying a methodology for the spatial estimation of meteorological variables through geospatial models.

The methodology includes data cleansing and validation to identify and correct outliers or errors, the assessment of model accuracy through cross-validation techniques, and a detailed analysis of the spatial and temporal variability of the data based on data availability in hydrometeorological stations.

A geostatistical analysis is conducted, adapted to the peculiarities of each measured hydrometeorological variable, considering relationships with other meteorological variables and secondary information such as altitude, latitude, longitude, and terrain aspect, using multivariable regressions. This improved the data estimation quality due to high correlations between variables.

The generation of data grids and their subsequent interpolation allow the creation of detailed maps of hydrometeorological variables in areas without monitoring stations, providing a more comprehensive and detailed view of environmental conditions. The uncertainty associated with the results is evaluated and presented to interpret the generated maps properly.

This study, conducted in a Colombian watershed, highlights the applicability of this methodology in basins with limited information. For this purpose, data and maps of temperature, evapotranspiration, and precipitation were generated at different space-time scales of interest, in addition to estimating multi-temporal potential recharge maps.

How to cite: Donado, L. D. and Mercado, O.: Generation of spatial grids for hydrometeorological data for estimation of groundwater recharge in tropical aquifers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20744, https://doi.org/10.5194/egusphere-egu24-20744, 2024.

 This study examines the groundwater potential of the Agia aquifer, Crete, Greece,  under the existing water management policies.  Alternative future scenarios of groundwater abstraction and/or climate projections are also examined. The Agia Springs area is characterized by rich groundwater supplies which are used to meet water demand for drinking and irrigation  for the  Chania region. This region belongs to one of the most productive valleys on the island of Crete and plays an important role in the agricultural - food sector. It is also characterized by intensive tourist development. Therefore, the demand for water is higher in the summer season than in the rainy season, which leads to strong seasonal fluctuations. At the same time, the water supply is declining as precipitation is lower than in previous decades.  Climate scenarios presented for the island of Crete,  predict a 20% decrease in rainfall in the near future.The relevant authorities have drawn up a water management plan, which is currently being updated in order to mitigate the problems arising from the increasing demand.  According to the new scheme of the Agia Springs, the total withdrawal is 26 hm³/year, while there is a potential of 31.5 hm³/year. The aim of this study is to model the groundwater flow of the Agia aquifer in order to develop scenarios that could allow full utilization of the groundwater potential and reform the contribution of groundwater resources to the region’s water balance. The groundwater flow simulations were carried out using the Princeton Transport Code (PTC) and the ARGUS ONE 4.2.0.w program. The model considers the hydrogeological characteristics of the area, the precipitation time series, and the pumping rates of the extraction wells. The calibration of the model has shown that the Agia Springs field is a complicated confined aquifer system with large depth values (more than 400 m below sea level). The calibration shows better performance during the dry periods, with a good correlation between the modeled results and the values of the groundwater measurements on site. The final proposed scenarios refer to: 1) the short-term scenario, in which three additional pumping wells are operated alongside the existing ones, resulting in 29 hm³/year and 2) the medium -term scenario, which considers the pumping wells of the short-term scenario and four new ones, providing an additional 5 hm³/year. The results show that there is no significant impact on the response of the springs. The level of the springs deteriorates during the additional pumping. However, it recovers with the interruption of the operation of the pumping wells, which indicates the resilience of the aquifer.

Acknowledgment

This work was supported by OurMED “ Sustainable  water storage and distribution in the Mediterranean” project, funded by the PRIMA Programme supported by the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No 2222

References

Babu, D.K, Pinder, G.F., Niemi A., Ahlfeld, D.P. and Stothoff, S.A., 2002. Chemical Transport by Three-Dimensional Groundwater Flows, argusone.com.

Perleros, C., and Vozinakis, K., 2002. Hydrological study of the Chania county, geological map, Organization for Development of West Crete (ODWC)

How to cite: Karatzas, G., Varouchakis, E., Anyfanti, I., and Nikolaidis, N.: Modeling the groundwater flow of the Agia karstic aquifer in Crete, Greece under present and future conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12562, https://doi.org/10.5194/egusphere-egu24-12562, 2024.

One of our planet’s most significant and important widely available resources is groundwater, which is also a major global source of water for domestic, agricultural and industrial uses. Subterranean aquifers typically provide over 40% of the water consumed by California’s towns and farmers, and a substantial amount more during the drought years. Since aquifers are influenced by both natural and anthropogenic processes, groundwater pollution is a major issue worldwide. Ecosystem functions, human health, and socio-economic development, all depend on the quality of the water that it used in different sectors. In order to guarantee the safe and sustainable use of these resources for a variety of purposes, it is crucial to evaluate and monitor the quality of groundwater. In this study, the groundwater quality for the state of California, United States was evaluated using Weighted Index Overlay Analysis to establish the suitability of it for human consumption. The dataset utilized in the study was hosted by the California State Water Resources Control Board (CSWRCB).

Groundwater data collected from CSWRCB website on physiochemical parameters, such as total dissolved solids, total hardness and main cations like Ca²⁺, Mg²⁺, Na⁺ & K⁺ as well as anions like HCO₃^-, Cl^-, SO₄^2- & NO₃^-  were analysed to determine the quality of groundwater in California. Using the Inverse Distance Weighted (IDW) approach for interpolation, spatial maps were generated in ArcMap. In accordance with WHO drinking water quality guidelines, weights have been allocated to several physiochemical characteristics for the Weighted Index Overlay Analysis (WIOA).  California's groundwater quality's temporal variation is assessed for last 15 years to investigate the evolution of groundwater usability for drinking in the state.

                           Figure 1. Flowchart showcasing WIOA working procedure for groundwater quality assessment for drinking purpose

How to cite: Das, A., Banerjee, D., and Ganguly, S.: Assessment of the evolution of groundwater quality for the state of California, United States using weighted index overlay analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8383, https://doi.org/10.5194/egusphere-egu24-8383, 2024.

The management of groundwater under arid climate conditions represents one of the biggest challenges, and the ongoing trend of climate change suggests that it will result to be even more urgent. This is especially true if we consider the interaction between water, the porous medium and other phases, such as minerals. For example, exploitation/conservation of salt lakes/lagoons, limit salinization of soil and land desertification, study the alteration of soil’s mechanical properties and reliability of wastewater disposal are human activities that are strictly connected to groundwater dynamics and climate regimes. For this reason, more investigation is needed to understand how the complex system composed of surface conditions and the groundwater body, including chemical reactions, works. In this study, the focus is on the interplay between the mixing that occur in the aquifer due to variable density flow and mineral precipitation from the saline water. Variations in groundwater density are relevant in such systems, where the evaporation drives upward the water flow and reconcentrates the solutes at the exposed aquifer surface. The increase in water density with salinity confined to a layer which lays on less dense water may lead to a gravitationally unstable condition. From this stage, saline fingers originate, grow, and sink in the aquifer, establishing a free convective flow throughout the whole thickness. This mechanism forces the solutes to sink to the deeper zones and leave the saline water, from which minerals can precipitate. Here we present a variable-density flow model coupled to reactive transport to replicate a typical salt-lake environment connected to the aquifer beneath, i.e., under saturated conditions. These conditions are obtained by imposing a constant evaporation rate at a segment of the top boundary and a constant pressure at the inlet top boundary, to allow the water to enter while it evaporates. The chemistry of the initial and recharge water is the same to observe the modifications to different parts of the system due to convective flow and reactions. A series of simulations was run, changing the evaporation rate and permeability, corresponding to different Rayleigh numbers, to understand their effects on fluid dynamics and mineral formation. The results show that a saline layer forms at the surface, diffuses, and eventually becomes unstable under steep density gradients. The formation of fingers and dynamic of convection are different among those simulations but for long times the system faces a chemical (and density) stratification where the freshwater flow is constrained progressively toward the surface by the convective cell, which affect in turn the transport toward the unstable saline layer. Evaporation and permeability have different influence and weight in the system, determining how a system would evolve in time. The precipitation of minerals limits the convective flow, on the other hand, spatial distribution of minerals depends on the features of convection, and so, evaporation and permeability. In addition, these two parameters are modified by minerals in porosity.

How to cite: Pieretti, M., Abarca, E., and Cueto, L.: Evaporation-driven convective mixing and mineral precipitation in groundwater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11662, https://doi.org/10.5194/egusphere-egu24-11662, 2024.

How to cite: Erőss, A., Baják, P., Mezei, M. M., Csiszár, E., Hegedűs-Csondor, K., Izsák, B., Vargha, M., Czuppon, G., and Horváth, Á.: Spatial and temporal variabiliy in drinking water quality in a riverbank filtered drinking water supply system  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13213, https://doi.org/10.5194/egusphere-egu24-13213, 2024.

In coastal regions, where about 40% of world population is settled, freshwater aquifers are affected by a saltwater intrusion. The presence of elevate salt concentrations, among the most common pollutants in groundwater aquifers, represents a world-wide spread problem for coastal areas, such as Mediterranean coasts, both East and West coasts in the U. S., Gulf of Mexico and Middle East coasts. The seriousness of the situation is enhanced by the high demand of water supply, especially in the drier periods, and by the mean sea-level rise due to climate change. So that seawater will encroach farther inland and will threaten the available fresh groundwater supply, affecting not only human livelihood, but also coastal ecosystems. The form and transformation of the seaward hydraulic gradient of the aquifer and a constant freshwater discharge into the sea are fundamental in order to control the rate of intrusion.

To maintain the seaward gradient in the system the aquifer may be artificially recharged by freshwater by increasing the inland piezometric heads. The purpose of this solution is to create a hydraulic barrier against the inland flow of saline water by injecting freshwater in the vicinity of the shoreline. For phreatic aquifers both injection wells and surface spreading of water, such as irrigation, may be applied. Surface reservoirs, lakes and canals can be used as recharge systems for unconfined aquifers through freshwater infiltration (Hussain et al., 2019).

To assess the effectiveness of this mitigation approach and the amount of volumes of freshwater required, physical experiments are developed in a laboratory canal developed to reproduce a controlled heterogeneous porous media.

The sandbox measures 500 cm long by 30 cm wide by 60 cm high, with 3 cm thick plexiglass walls. Two tanks are located upstream and downstream from the sandbox, with volumes of about 0.5 m³ and 2.0 m³, respectively. The upstream tank is filled with fresh-water and is continuously supplied by a small pump, providing fresh-water recharge. The downstream tank is filled with salt-water, previously prepared by adding salt to fresh-water till a proper density is reached, and it represents the sea. This canal has been used in previous works (Bouzaglou et al., 2018, Crestani et al., 2022), but in the present the homogeneous porous media has been substituted by three different nominal size ranges of glass beads, equal to 0.3-0.4, 0.4-0.8 and 1.0-1.3 mm respectively, organized in 250 cells, each of size 20x30x5 cm³ to reproduce a prescribed statistical anisotropic structure.

The evidences deduced from the physical experiments developed simulating the seawater intrusion-retreat phenomenon due to drought periods are discussed in comparison with the results of a numerical model.

How to cite: Salandin, P., Belluco, E., Camporese, M., Crestani, E., Darvini, G., Giaretta, P., and Mazzarotto, G.: Mitigation strategies against seawater intrusion in the context of climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20071, https://doi.org/10.5194/egusphere-egu24-20071, 2024.

Computational burden, resulting from intensive executions of simulators during optimisation, often hinders the application of the simulation-optimisation (SO) methods for deriving optimal pumping schemes in coastal groundwater management, and impedes conducting sensitivity analysis of optimal pumping strategies to management constraints. For quickly identifying optimal pumping strategies under various constraints, this study develops an efficient framework, where adopting a lower-resolution simulator generates data to build surrogate models with a novel offline training algorithm and then applying a global optimization algorithm to determine optimal solutions according to the surrogate predictions. Traditional offline training approach involves developing surrogates before optimisation, often using training datasets that cover the input space either uniformly or randomly, which can prove inefficient due to potential oversampling of low-gradient areas and under-sampling of high-gradient areas. This study proposes an iterative search algorithm that efficiently selects training points by first scoring each unknown point based on its distance to the closest training point and the gradient of the surrogate estimate and then choosing the input candidate with the maximum score as the next sampling point. The proposed surrogate-based optimisation framework is applied to solve a two-objective groundwater management problem formulated on a three-dimensional island aquifer, using hydrogeological conditions representative of San Salvador Island, Bahamas. The goal is to minimize the operation cost resulting from groundwater pumping and desalination, while maximizing the amount of qualified groundwater supply, subject to constraints on seawater intrusion (SWI) control, expressed in terms of aquifer drawdown and salt mass increase in the aquifer.
Gaussian Process (GP) techniques are employed to construct model surrogates, predicting management objectives and constraint values, alongside quantifying associated uncertainties. By conducting repeated Monte Carlo simulations using these GP models, it becomes possible to ascertain the probability of Pareto optimality for each pumping scheme. Derived optimal pumping schemes are characterized by the Pareto-optimal probabilities and validated by the higher-resolution simulator. Results indicate that the proposed surrogate-based multi-objective optimisation framework can efficiently provide trustable optimal pumping schemes and be used to analyse the sensitivity of optimal groundwater supply cost to the constraints.

How to cite: Bau, D., Yu, W., Mayer, A., and Geranmehr, M.: Efficient surrogate-based multi-objective optimisation for sustainable island groundwater management, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17853, https://doi.org/10.5194/egusphere-egu24-17853, 2024.

Understanding the interactions between ditch water levels, soil water and groundwater levels in drained lowlands is crucial for agricultural management, particularly under climate change with an increase both in flooding frequency and severity in winter and water scarcity for crop production in the vegetation season. The optimum quantity of water in the subsurface soil is the base for high yields, both on fields and on grassland. Water retention with weirs or sills in the ditches is a possible way to improve water availability in the adjacent areas. The aim of our study is to clarify the influence of ditch water management on groundwater dynamics and by this on soil water content.

Observations were conducted over a transect near Werenzhain, a Lusation village (Germany, south of Brandenburg). Field measurements encompassed the collection of meteorological data essential for calculating potential evapotranspiration. Soil water content was meticulously monitored at various depths (10, 20, 30, 40, 60, and 100 cm), alongside soil tension measurements at depths of 30, 60, 90, and 120 cm. In the laboratory, soil hydraulic properties, texture, and bulk density were measured for these corresponding depths. Additionally, fluctuations in the groundwater level during the study period were observed down to 300 cm. First, measured groundwater levels were simulated using HYDRUS 2D to obtain the dynamics between ditch water and shallow groundwater. Thereafter, different sets of ditch water levels were used to predict the soil water and groundwater levels for vegetation season. Our approach successfully simulated data with observed soil water content, soil water tension, and groundwater level throughout the study period. Further, we could model scenarios for an optimized ditch water level management.

How to cite: Joshi, D. C., Hildmann, C., Schlepphorst, R., and Zimmermann, B.: Interaction of surface water and groundwater on agricultural plots: Insights from field measurements and numerical modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17101, https://doi.org/10.5194/egusphere-egu24-17101, 2024.

Most African populations depend on groundwater in rural areas for their drinking water. Indeed, in the face of climate change and strong demographic growth, groundwater is increasingly in demand. The sustainability of water resources in this type of environment is becoming a major challenge. Managed Aquifer Recharge (MAR), which consists of inducing water infiltration through appropriate developments to replenish an aquifer's water stock, is therefore one of the measures that can be implemented to secure water supplies, combat the effects of climate change and, more generally, contribute to improving groundwater availability. However, the issue of the effectiveness of MAR systems, depending on the type of environment, still remains. The aim of this research is to determine the influence of aquifer and infiltration basin properties on artificial recharge, with a view to identifying the optimum conditions for setting up such a system.

Using synthetic modeling, we designed a representative domain of basement aquifers incorporating an infiltration basin. The hydrogeological properties of the different layers of the defined alteration profile were then determined, including the boundary conditions of the domain. The study involved varying the various physical characteristics of each layer, such as hydraulic conductivity (homogeneous and inhomogeneous), vadose zone thickness, storage, water table thickness and hydraulic gradient, and the characteristics of the infiltration basin, such as effective infiltration, recharge time, geometry and loading conditions (constant hydraulic head, variable hydraulic head). These simulations were carried out under the FEFLOW numerical model in both saturated and unsaturated zones, in order to test different solutions. The results of the simulations were then compared with those obtained using the Hantush analytical solution. These comparisons not only validated the model results, but also enabled us to carry out a sensitivity analysis of the validity range of the analytical solution by reproducing the different scenarios. This study presents an original approach both in terms of its methodology (analytical model, numerical model, application model) and its implementation in a basement zone and West African context.

The results show that simulations in saturated and unsaturated conditions are virtually identical. Most scenarios show a strong relaxation (1 to 2 days) after the injection time. The main parameters influencing recharge and relaxation are hydraulic conductivity, storage, unsaturated zone thickness and effective infiltration in the infiltration basin, while the hydraulic gradient has no significant influence. In addition, infiltration basins with variable hydraulic head (flow injection) performed better in terms of recharge (13 m difference) than basins with constant hydraulic heading. Finally, these results have enabled us to establish different hydraulic head curves as a function of different aquifer and seepage basin parameters, enabling effective inter-comparison.

Keywords: Basement area, FEFLOW, Infiltration basin, MAR, Modelling.

How to cite: Doulkom, P. A. M., Koïta, M., Rossier, Y., Vouillamoz, J.-M., Biaou, A. C., Lawson, F., Kafando, M. B., Yonaba, O. R., and Mounirou, L. A.: Evaluation of optimal conditions for managed aquifer recharge in the west African basement area., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16890, https://doi.org/10.5194/egusphere-egu24-16890, 2024.

Across 2021 and 2023, Northern Italy suffered a harsh meteorological drought due to severely under the norm precipitation. This strongly affected the pre-alpine lake levels as well as rivers discharge and soil moisture. Groundwater was also impacted, resulting in decreased water table levels. These factors led to harsh consequences on agriculture, that in Lombardy region largely relies on flooding and surface irrigation methods using Ticino and Adda rivers water coming from lakes.

To address the challenges posed by this last drought event and to be prepared to possible future dry scenarios, we propose and show the first results of our research around the possibility to harness the capillary irrigation network as an infrastructure for a diffused managed aquifer recharge (MAR). The main idea is to infiltrate water into aquifers in periods of surface water exceedance (historically autumn/winter in this region) using the irrigation network by keeping water in the channels or providing it as irrigation. The increased underground water storage would lead to groundwater levels increase. Relying on the slow groundwater velocity (ca. 350 m/year), water would remain stored in the subsoil just below the irrigated areas, bringing two main advantages during the following spring and summer seasons. First, the possibility to harness groundwater as an additional reservoir from which to extract water for agricultural or urban purposes if surface and meteorological water is insufficient. Second, a sustained flow rate at lowland springs that are scattered around the Po plain, whose water is reused for irrigation downstream and represent biodiversity hotspots. The adaptation measure feasibility will be assessed through field tests by providing water in channels and on fields and through agricultural and groundwater integrated models able to consider climate change scenarios.

During the 2023/24 winter season, a first field test was carried out distributing water in the irrigation network and over some fields selected through the cooperation of farmers. Helped by a regional scale numerical model we tested the potentiality of such practice both at basin and at local scale, by simulating the additional winter recharge. The model simulations clearly show the adaptation measure potentiality both at local and at regional scale. Furthermore, monitored wells around the pilot are showing signs of the expected short-term effects of the measure, but a longer time series is needed to assess its actual impacts. Here some model simulation outcomes are shown together with the first results of the field activities, which are the first steps for planning the main experimental activity planned for the next winter season.

This research is funded by the Interreg Central-Europe programme, as part of Pilot Action Milan from MAURICE project (CE0100184): MAnagement of Urban water Resources In Central Europe facing climate change). The project involves other research and public administration entities from a total of 6 countries involved.

How to cite: Colombo, P., Mazzon, P., and Alberti, L.: Off-season irrigation as a climate adaptation strategy for future groundwater management in Northern Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15617, https://doi.org/10.5194/egusphere-egu24-15617, 2024.

Groundwater is a vital resource for direct consumption as well as for agriculture, particularly in arid and semiarid climates where groundwater is often a primary water source for irrigation. Here, we analyze more than 170,000 groundwater level timeseries across the globe. We show that groundwater level declines accelerated over the past four decades. Accelerated declines are especially widespread in dry regions with extensive cropland. However, our study also reveals that there are areas where interventions have led to groundwater levels to recover.  This result provides a ray of hope for sustainable management of vital groundwater resources in the decades to come.

How to cite: Seybold, H., Jasechko, S., Perrone, D., Fan Reinfelder, Y., Taylor, R., Shamsudduha, M., Fallatah, O., and Kirchner, J.: Accelerated Decline of Groundwater Levels in the 21st century, globally, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12170, https://doi.org/10.5194/egusphere-egu24-12170, 2024.

Groundwater level decline and quality deterioration is continuously observed nationwide in South Korea. Meanwhile, the demand for groundwater, which is relatively stable and clean in the face of climate crisis and future industry, is increasing in South Korea. In order to meet sustainable use for growing groundwater demand, it is essential to assess groundwater resources sustainability by taking into account the economic, social, and environmental factors in management and planning of groundwater resources. This study proposes groundwater sustainability management indicators to account for these factors based on DPSIR framework. A case study is performed to assess groundwater resources sustainability on 5 river basins(Han-river, Keum-river, Nakdong-river, Youngsan-river, Seomjin-river) by using indicators with available data in South Korea. The results show that groundwater depletion and contamination is susceptible to occur nationwide with spatial variation. Renewable groundwater resources per capita is evaluated to be approximately ranged from 1,000 to 10,000 m³/yr over the nation, while less than 1,000 m³/yr in the western and southeastern parts of South Korea, which is related to high population and urbanization. Much of Groundwater abstraction occurs with respect to groundwater recharge in the easter areas. Among 5 river basins, groundwater dependence of Geum-river basin area is highest. Overall, the wester parts of Korea including Keum-river, Youngsan-river, Seomjin-river basins, are susceptible to be more stressed. Total nitrogen load is high in subbasins of Han-river and Keum-river basins, but groundwater quality index for nitrate-nitrogen shows different spatial patterns. In South Korea, total e-coli, NO³-N, and Cl- are major contaminants observed in groundwater. The case study shows that proposed groundwater sustainability management indicators can good enough to provide a general view of groundwater resources status. Proposed indicators can also be utilized to evaluate current status of groundwater and policies for National Water Management Basic Plan as well as used as elemental indicators for developing a comprehensive index for necessity. Further data collection and analysis is required for comprehensive assessment of groundwater resources management sustainability.

How to cite: Hyun, Y., Cha, E.-J., Jeong, A., and Han, H.: Indicator-based assessment of groundwater resources sustainability in South Korea, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15335, https://doi.org/10.5194/egusphere-egu24-15335, 2024.

The satellite initiative Gravity Recovery and Climate Experiment (GRACE) has been thoroughly investigated in recent years to monitor groundwater storage (GWS). Since 2002, GRACE has provided distinctive perspectives on fluctuations in Earth's gravity field. Changes in gravity over time serve as valuable indicators for deducing alterations in total terrestrial water storage (TWS), encompassing soil moisture, surface water, snow and ice, canopy interception, wet biomass, and groundwater.

The importance of GRACE data in determining GWS holds crucial implications, particularly in regions with limited hydrogeological information. Numerous analyses published so far have consistently demonstrated a robust correlation between GWS derived from GRACE and measurements obtained directly from wells in extensive aquifers.

The Global Land Data Assimilation System (GLDAS) combines satellite and in situ data with sophisticated land surface modeling and data assimilation techniques. In the NASA GLDAS System Version 2 (GLDAS-2), GRACE data, initially on a 1° global grid, is downscaled to a higher resolution of 0.25°. This extension of data covers a daily scale from 1948, effectively interpolating temporal gaps present in the GRACE dataset. Following the isolation of contributions to temporal mass changes, GLDAS furnishes daily time series for GWS, making the GWS data readily available for utilization.

The present study adds to the existing body of knowledge by showcasing that GRACE is skilled at capturing regionally averaged seasonal variations in observed GWS at two Spanish detritic aquifers: Almonte- Marismas and Alto Guadalentín. Even in these cases, where the study area is relatively small compared to the broader GRACE track, there are good correlations between in situ and satellite information. On the other hand, this work aims to assess the efficacy of readily accessible GWS data obtained from the GLDAS web services. This will be accomplished through the validation of GWS ready-to-use product from GLDAS involving (i) an examination of its correlation with piezometric information in both confined and unconfined aquifers, and (ii) an evaluation of net groundwater recharge rates computed by using GWS data.

How to cite: Guardiola-Albert, C., Naranjo-Fernández, N., Rivera-Rivera, J. S., Gómez Fontalva, J. M., Aguilera, H., Ruíz-Bermudo, F., and Rodríguez-Rodríguez, M.: Assessment of groundwater storage variation at aquifer scale with ready-to-use GRACE Satellite Data: Spanish study cases, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12755, https://doi.org/10.5194/egusphere-egu24-12755, 2024.

During 1992-2022 excessive withdrawal groundwater caused large-scale aquifer-system compaction and land subsidence in the Choshui River Alluvial Fan (CRAF) in Taiwan. How to effectively monitor land subsidence has become a major issue in Taiwan. In this paper, we introduce a multiple-sensor monitoring system for detecting land subsidence in central Taiwan, including 46 continuous operation reference stations (CORS), multi-temporal InSAR (MT-InSAR), a 1000-km leveling network, 36 multi-layer compaction monitoring wells, 7 automatic record extensometers, and 223 groundwater monitoring wells. This system can monitor the areal extent of land subsidence and provide data for studying the mechanism of land subsidence. We also develop new low-cost high-performance GNSS equipment and automatic multi-layer compaction monitoring equipment to monitor different aquifer compaction. We also use the Internet of Things (IoT) technology to control and manage the sensors and develop a big data processing procedure to analyse the data from the system of sensors. The procedure makes land subsidence monitoring more efficient and intelligent.

How to cite: Hung, W.-C., Lin, S.-H., Chen, Y.-A., and Lin, G.-Z.: Multi-sensor System for Detecting Land Subsidence in Central Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10022, https://doi.org/10.5194/egusphere-egu24-10022, 2024.

Rapid urbanization, fast population growth, agricultural and economic development increase the over-drafting of groundwater resources worldwide, which leads to induced land subsidence results in infrastructure damage and loss of the aquifer's storage capacity (Famiglietti et al., 2015; Galloway and Burbey, 2011). In the North Indian region, the GRACE satellite has observed a total water storage loss of about 19.2 Gt yr^-1 (Rodell et al. 2018). Thus, this research is focused on two study areas, Chandigarh and SAS Nagar regions in North India, to analyze the compaction of aquifer systems and groundwater dynamics. We implement the Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique exploring ascending (175 imageries) and descending (170 imageries) passes of Sentienl-1 SAR sensor data of the European Space Agency (ESA) over the study area from 2016 to 2022. The InSAR processing was done for each data stack using an open-source GMTSAR software following a Small BAseline Subset (SBAS) method to generate line-of-sight (LOS) deformation maps (Berardino et al., 2002; Sandwell et al., 2011). The ascending and descending LOS results were further combined, generating vertical land motion (VLM) following Fuhrmann & Garthwaite (2019) approach. We explored and analyzed 12 groundwater head-level data over the study area and integrated with InSAR-derived VLM in a hydro-geophysical model to examine various mechanical characteristics of the aquifer systems (Ojha et al., 2018). Such properties include elastic and inelastic storage coefficients, the aquifer's capacity loss, permanent and seasonal storage loss, etc. The result exhibits a deformation signal of 18 cm/year in Mohali, 16 cm/year in Kharar, 17 cm/year in Dera Bassi, 12 cm/year in Lalru region of SAS Nagar districts, and  8 cm/year of land subsidence in southeast parts of Chandigarh region. We noticed a GW storage loss capacity of about 1.15% of the total aquifer system during the study periods, which occurs due to the inelastic compaction of the aquifer, and the total volume of GW storage loss is about 3 km³. The InSAR-integrated GW observations will provide precise information on understanding groundwater storage change, a necessary precondition for effective water management strategy over such stressed aquifer systems.

References

Berardino, P., G. Fornaro, R. Lanari, and E. Sansosti. 2002. "A New Algorithm for Surface Deformation Monitoring Based on Small Baseline Differential SAR Interferograms." IEEE Transactions on Geoscience and Remote Sensing 40 (11): 2375–83. https://doi.org/10.1109/TGRS.2002.803792.

Famiglietti, J. S., A. Cazenave, A. Eicker, J. T. Reager, M. Rodell, and I. Velicogna. 2015. "Satellites Provide the Big Picture." Science 349 (6249): 684–85. https://doi.org/10.1126/science.aac9238.

Fuhrmann, Thomas, and Matthew C. Garthwaite. 2019. "Resolving Three-Dimensional Surface Motion with InSAR: Constraints from Multi-Geometry Data Fusion." Remote Sensing 11 (3): 241. https://doi.org/10.3390/rs11030241.

Galloway, Devin L, and Thomas J Burbey. 2011. "Regional Land Subsidence Accompanying Groundwater Extraction." Hydrogeology Journal 19 (8): 1459.

Ojha, Chandrakanta, Manoochehr Shirzaei, Susanna Werth, Donald F. Argus, and Tom G. Farr. 2018. "Sustained Groundwater Loss in California's Central Valley Exacerbated by Intense Drought Periods." Water Resources Research 54 (7): 4449–60. https://doi.org/10.1029/2017WR022250.

Sandwell, David, Rob Mellors, Xiaopeng Tong, Matt Wei, and Paul Wessel. 2011. "GMTSAR: An InSAR Processing System Based on Generic Mapping Tools," May. https://escholarship.org/uc/item/8zq2c02m.

How to cite: Chawla, S. and Ojha, C.: Groundwater Dynamics and Aquifer Mechanical Properties over North Indian Region using MT-InSAR technique , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-501, https://doi.org/10.5194/egusphere-egu24-501, 2024.

Armed conflicts have a pronounced impact on the environment, leading to changes in land use/land cover (LULC) and water resources. The Orontes River Basin (ORB), which covers parts of Lebanon, Syria, and Turkey, represents a unique case study.  After a prolonged period of intensive groundwater abstraction in the ORB, the Syrian War has led to cropland abandonment in certain areas, whereas continued intensive agriculture persisted in others. Groundwater levels are expected to have recovered due to conflict-related LULC changes and, consequentially, reduced irrigation demands. However, direct observation of this recovery is impeded due the near-complete lack of traditional hydrological or hydrogeological data in the Syrian portion of the ORB.

Just as overexploitation of groundwater can result in land subsidence, groundwater recovery may manifest itself as land surface uplift, given suitable poro-elastic properties of the subsurface hydrogeological units. In order to infer regional groundwater dynamics across the ORB, we use interferometric synthetic aperture radar (InSAR) to detect land uplift and subsidence. Our results show complex transient, non-uniform trends in subsidence/uplift due to conflict-induced changes to LULC and groundwater exploitation across the ORB. The results of this study can be used for optimizing humanitarian aid and as model inputs for future hydrological models in areas where in-situ measurements are almost non-existent.

How to cite: Mhanna, S., Halloran, L., and Brunner, P.: Groundwater, armed conflict, and land surface uplift: an InSAR analysis of the Orontes River Basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5577, https://doi.org/10.5194/egusphere-egu24-5577, 2024.

Studying water level fluctuation is crucial for water resource management and infrastructures. Groundwater level variations are due to recharge and/or discharge of water from aquifer because of anthropogenic activities or natural processes, e.g., rainfalls, irrigations, etc. Such variations may have a direct impact on ground deformation in the form land subsidence, land uplift, or landslide. Persistent Scatterers Interferometric Synthetic Aperture Radar (PS-InSAR) is an advanced satellite remote sensing technique which allows an effective monitoring of ground movement. In this work, PS-InSAR time series as well as precipitation and hydrological time series in a region in Catania, Italy are utilized, and their possible interconnections are investigated in the time-frequency domain using the tools in the least-squares wavelet software. It is shown how water level (surface water and groundwater) variations may have an impact on ground deformation.

How to cite: Ghaderpour, E. and Scarascia Mugnozza, G.: Ground Deformation Monitoring Using InSAR and Hydrological Time Series and Least-Squares Wavelet Software: A Case Study in Catania, Italy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9616, https://doi.org/10.5194/egusphere-egu24-9616, 2024.

The impact of climate change was reported to cause more frequently extreme rainfall or drought events in decades. The disaster like typhoon coming up with excessive rainfall would flood low-lying coastal areas, resulting in devastating damage to local industry. Moreover, the coastal area may also be threatened by relative sea level rise due the lowering land surface height by land subsidence hazards. The Pingtung Plain, one of the major aquaculture-rich counties in Taiwan, suffered from up to 3.5-meter cumulative subsidence in the coastal area from 1972 to 2019. Featuring tropical monsoon climate properties, the land displacement in Pingtung area is highly variated with interannually seasonal changes between dry and rainy seasons. In this study, we apply Persistent Scatterer InSAR (PSI) technique into the high variability coastal area to make up for the lack of either spatial or temporal resolution of in-situ grounded measurements like continuous GNSS station or precision leveling. To comprehensively analyze the transient land deformation responded within a short period, we further employ an unsupervised decomposition method called Principal Component Analysis (PCA) into InSAR observation matrix to distinguish individually spatiotemporal patterns. First two principal components (PCs) reveal that the coastal and inland area in the Pingtung Plain characterize different amplitude of seasonal variations and long-term trends. In addition, the third principal component indicates the heterogeneous patterns due to different types of industrial groundwater usage and hydrogeological environment. The unsupervised method is capable to retrieve different spatial deformation patterns in the high variability coastal area from the bulk InSAR time-series matrix, which can contribute to comprehensive understandings of the relation between land deformation and aquifer system.

How to cite: Lin, S.-H., Hung, W.-C., and Hu, J.-C.: InSAR Decomposition Reveals Varied Deformation Patterns in Coastal Subsidence Regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15224, https://doi.org/10.5194/egusphere-egu24-15224, 2024.

In recent decades, the increasing water demand in Iran has led to extensive groundwater pumping, which has caused significant depletion of many aquifers across the country. This unsustainable extraction has resulted in the loss of groundwater resources and significant land subsidence, adversely affecting several agricultural and urban areas. While previous studies have identified the problem at local scales in major agricultural centers and metropolitan areas, the extent of land subsidence and its impact on groundwater resources, population, and infrastructure across the country is still unknown. This study aims to fill this gap by extending the monitoring and providing a comprehensive understanding of the issue through a nationwide survey that employs Interferometric Synthetic Aperture Radar (InSAR). We generate a large stack of small baseline interferograms at a spatial resolution of 100 meters. Assuming land subsidence is spatially localized and temporally correlated, we remove other signals, mainly from atmospheric phase delay, to isolate the subsidence. Our analysis of Sentinel-1 data from 2014 to the present has enabled us to map the subsidence rates across the country. Our findings indicate that over 50,000 sq. km of the country's land is experiencing significant land subsidence, primarily in agricultural areas, but also in urban areas. As this subsidence is associated with pumping from confined aquifers, we estimate an annual groundwater loss of almost 2 Billion Cubic Meters in Iran, which is in agreement with independent in-situ measurements and GRACE data. By combining our estimated groundwater loss with a land cover map and official agricultural production data, we explore how inefficient irrigation in certain parts of the country is the main driver of groundwater loss. Our study underscores the urgent need for immediate measures to address the issue of groundwater loss in Iran and mitigate its effects on the country's population and infrastructure.

How to cite: Haghshenas Haghighi, M. and Motagh, M.: The growing groundwater crisis in Iran and its impact on land subsidence: A nationwide survey using satellite InSAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15656, https://doi.org/10.5194/egusphere-egu24-15656, 2024.

The growing average air temperature and rapid urbanization deepen the urban heat island (UHI) phenomenon, which mainly affects large cities. Urban areas contribute to changes in the local atmospheric environment but also groundwater. The impact of these changes on the thermal regime of groundwater is documented all over the world by the increased temperature of groundwater in city centers compared to the surrounding rural areas. However, this relationship as well as the impact of other factors on the subsurface urban heat island (SUHI) are not yet well understood. In the case of the city of Wrocław, characterized by an increase in average temperatures in recent decades and the identified UHI phenomenon, present-day the phenomenon of SUHI is unknown.

This work focuses on the analysis of maps of the spatial distribution of groundwater temperature in the city of Wroclaw (Poland), obtained using spatial interpolation. For this purpose, measurement data from 2004-2005 and 2022-2023 were used. In addition, an attempt has been made to compare the distribution of groundwater temperature with the Land Surface Temperature (LST) for each of the periods. In the next part of the work, the relationships between groundwater temperature and other factors such as: distance from the city center, distance from rivers, LST and UHI were determined. Generalized linear regression was used to indicate which factors influence the subsurface urban heat island (SUHI). The highest rate was given to the distance from the city center (R2=0.49).

How to cite: Hajnrych, M. and Worsa-Kozak, M.: Factors influencing the subsurface urban heat island in the city of Wrocław (Poland), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17454, https://doi.org/10.5194/egusphere-egu24-17454, 2024.

Actively monitoring ground motion is of the highest importance in The Netherlands, a country in
which many of its regions lie below sea level. Water tables in the country have been managed
for centuries by using a system of dams, dikes and canals through which excess water can be
pumped away to allow for the prevention of flooding, and for the reclamation of submerged land.
However, the effects of centuries of active water management in the region have resulted in
significant land subsidence, and its effects are being felt as it is becoming a significant threat to
the future of the country as sea levels continue to rise [1].
This has created the need to monitor land surface motion at large spatial scales with frequent
temporal sampling. While InSAR is a promising candidate for such a task, the technique often
suffers from drastic losses of signal quality in the spring and summer months when used to
produce time series observations of peatlands. This significantly limits the effectiveness of
InSAR as a tool to monitor peatland surface dynamics [2,3,4].
We present the preliminary results of peatland surface motion using a novel InSAR processing
method which is designed to overcome the issues which have prevented its application over
northern peatlands in the past [5]. This work is the first large scale analysis of the Dutch Green
Heart region made with InSAR, providing land surface motion time series data at the parcel
scale for a 2000 km2 region with sub-weekly sampling over the period Jan. 2015 to Oct. 2023.
Our presentation will briefly outline the results, validation efforts and the various challenges
involved.
References
[1] G. Erkens, M. J. van der Meulen, and H. Middelkoop, “Double Trouble: Subsidence and CO2 Respiration Due to
1,000 Years of Dutch Coastal Peatlands Cultivation,” Hydrogeology Journal, vol. 24, no. 3, pp. 551–568, 2016.
[2] Y. Morishita and R. F. Hanssen, “Temporal decorrelation in L-, C-, and X-band satellite radar interferometry for
pasture on drained peat soils,” IEEE Transactions on Geoscience and Remote Sensing, vol. 53, no. 2, pp. 1096–
1104, 2015.
[3] Y. Morishita and R. F. Hanssen, “Deformation parameter estimation in low coherence areas using a multisatellite
InSAR approach,” IEEE Transactions on Geoscience and Remote Sensing, vol. 53, no. 8, pp. 4275–4283, 2015.
[4] L. Alshammari, D. J. Large, D. S. Boyd, A. Sowter, R. Anderson, R. Andersen, and S. Marsh, “Long-term peatland
condition assessment via surface motion monitoring using the ISBAS DInSAR technique over the flow country,
Scotland,” Remote Sensing, vol. 10, no. 7, 2018.
[5] P. Conroy, S. A. N. van Diepen, F. J. van Leijen, and R. F. Hanssen, “Bridging loss-of-lock in InSAR time series of
distributed scatterers,” IEEE Transactions on Geoscience and Remote Sensing, vol. 61, pp. 1–11, 2023

How to cite: Conroy, P., Lumban-Gaol, Y., van Diepen, S., van Leijen, F., and Hanssen, R.: Monitoring Dutch Peatland Subsidence Using InSAR – First Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21917, https://doi.org/10.5194/egusphere-egu24-21917, 2024.